Alkylation of dicyandiamide and formaldehyde resins



Patented Sept. 28, 1954 UNITED STATES PATENT OFFICE ALKYLATION FDICYANDIAMIDE AND FORMALDEHYDE RESINS i Lucien Sellet, Saddle River, N.J., and William O. Dawson, Amherst, N. H., assignors to Jacques Wolf &00., a corporation of New Jersey No Drawing. Application July 24, 1951,Serial No. 238,368

8 Claims. 1

This invention relates to a resinous material and the method of makingit. The invention relates, more particularly, to ethers of dicyandiamideand formaldehyde resin.

The dicyandiamide and formaldehyde resin, serving as the intermediatefor use in making the material of the present invention, is prepared asdescribed in application, Serial No. 103,953, filed July 9, 1949, byLucien Sellet and William O. Dawson for Dicyandiamide and FormaldehydeProduct and Method of Making" and issued as Patent No. 2,567,238 onSeptember 11, 1951. In brief, dicyandiamide, hereinafter sometimesreferred to as dicy, and formaldehyde in the proportion of 3.6-5 mols ofthe latter to l of dicy, are warmed in aqueous solution and at pHslightly above '7 until the material passes from the stage of theoriginal Water soluble mixture to a resinous polymethylol derivative ofdicy. It is considered that a large proportion of the product is thetetramethylol derivative of dicy or a polymer.

This dicy and formaldehyde resin possesses many advantages as anindustrial resin. It is, however, not soluble in large proportion inalcohol. When dissolved in water, the resin polymerizes on long standingin the aqueous solution and precipitates on mixing with an aqueoussolution of electrolytes.

The present invention relates to new resins some of which are free fromthe objections listed above to the methylol derivative and some of whichnew resins are free from one or more of these objections or have othernew and useful properties.

Briefly stated, the invention comprises the ethers of the polymethylolderivative of dicyandiamide and the method of making them. In thepreferred embodiment, the invention comprises the tetra-lower-alkylethers of dicy and formaldehyde resin that are soluble in alcohol,nonpolymerizing in aqueous solution, and not sensitive to electrolytesthat are precipitants of the dicy and formaldehyde resin.

As to starting materials, there is used dicy and formaldehyde resin inthe polymethylol stage. In a modification we make the finished resinfrom the raw materials in one step.

The alcohol to be used in the etherification with the resinouspolymethylol derivative of the dicy is suitably monohydric. In thatcase, the alcohol should be a lower water soluble alcohol, such as onecontaining 1 to 3 carbon atoms to the molecule. The alcohol may containsomewhat more carbons if the alcohol is polyhydric.

Examples of alcohols that meet the requirements and that may be used arethe monohydric aliphatic alcohols, methanol, ethanol, propanol andisopropanol; a polyhydric alcohol, as, for instance, ethylene,propylene, butylene, or diethylene glycol, glycerine, pentaerythritol,and sorbitol; and a sugar such as dextrose, levulose, and sucrose. Thesealcohols are unsubstituted. The alcohols may be used alone or mixed witheach other. The ethers made with the alcohols named above are soluble inwater. Water insoluble, higher alcohols may be used in a modification ofthe preferred method. Thus the ether made with a lower alcohol may beheated with the selected higher alcohol, to liberate the lower alcoholand leave the radical of the higher alcohol in the finished ether.Examples of the higher alcohols that may be used in this manner arebutyl, hexyl, octyl, dodecyl, and octadecyl alcohols.

Catalysts used to accelerate the etherification of the selected alcoholwith the dicy and formaldehyde resin are acidic. They are used toestablish the pH on the acid side below 7. Examples are acetic, formic,sulfuric, and hydrochloric acid, all used in aqueous solution.

The aldehyde for making the dicy resin and the alcohol foretherificaticn may be added jointly to the dicy. Thus the aldehyde andalcohol may be added together in a composition such as one now soldcommercially and representing paraformaldehyde or other form offormaldehyde either dissolved in the selected alcohol or combined partlyor wholly therewith in the form of an acetal or hemiacetal. In such acomposition. the aldehyde is first reacted with the dicy and thecondensation product formed is then etherifled, that is, alkylated withthe alcohol present. In fact, we usually react 4 mols of the alcohol inthe etherification reaction. Forthis purpose, we use to advantage anexcess of the alcohol as up to 25%50% above that required theoreticallyto form the ether with the polymethylol derivative of dicy. An excess ofthe alcohol is unobjectionable and is in fact desirable, particularlywhen the alcohol used is volatile and, there fore, readily removed fromthe etherified product or when an excess of the alcohol is of value inthe use to which the finished product is to be put.

The catalyst is used in proportions that vary somewhat with the rate ofreaction desired. Proportions within the range 0.1 to 1 mol for 1 mol ofthe dicy in the composition are adequate. Ordinarily we use around 0.2mol of the catalyst when it is a weak acid, such as an organic acid, andsmaller proportions when the acid used as catalyst is strong as in thecase of use of dilute sulfuric or hydrochloric acid. The acid should beadequate in amount to establish the pH below 7. Otherwise etherificationis objectionably slow.

As to conditions of manufacture, the selected alcohol and catalyst aremixed with dicy and formaldehyde resin. For this reaction, the anhydrouscondition, as, for example, an alcoholic solution, is best, water formedin the etherification being removed as the reaction proceeds.

When the resin is to be etherified with a polyhydric alcohol, the dicyresin made according to the said copending application is suitablyevaporated to dryness, the resulting solid dissolved in the polyhydricalcohol selected for the etherification or alkylation, and the catalystadded. The resulting solution is warmed for a few hours or until theetherification reaction is substantially complete.

Products made as described are useful in the tanning of leather,particularly when the alcohol used in making the ether is methanol,ethanol, or propanol. For such use, the etherified material in solutionis applied to pickled hides. The resin penetrates through the hide. Thenthe resin in the hide undergoes slow dealkylation or splitting followedby further polymerization under the influence of the acid therein or onthe addition of other acid, preferably an organic acid, acidic salts, ordilute sulfuric acid. It is considered that the acid causes liberationof the alkyl radical from the etherified resin, with resulting decreasein solubility and stability and ultimate polymerization causinginsolubility of the resin.

The products including those in which the resin is etherified with thepolyhydric alcohols are useful also in varnishes, resin finishingcompositions, textile printing compositions, and impregnatingcompositions such as giv shrinkage and grease-proof effects to textilesor impart increased tensile and wet strength to paper.

The manufacture of the dicy and formaldehyde resin, from which theetherified material is prepared, is effected as described in the saidcopending application. An example follows.

A three-neck flask equipped with condenser, thermometer, agitator andreflux condenser was charged with 84 parts by weight of dicyandiamide (1mol) and 292 parts of 38% formalin (3.? mols of formaldehyde), alongwith 1.8 parts of borax to adjust the pH to a level above 7. Agitationwas started and the temperature brought to refluxing, 95 C., and heldthere throughout the reaction. For a period of approximately 30 minutes,the mixture remained water soluble, that is, not precipitable ondilution with water, as described in the said Patent 2,567,238. Oncontinued heating, the condensation product became insoluble by the sametest, this showing formation of the desired intermediate product. After210 minutes heating, however, the condensation product again becameinfinitely soluble (dilutable) in cold water. The heating was thenstopped. If it is desired to dry the resin, the product is spray or drumdried.

Instead of preparing the dicy and formaldehyde resin in advance and thenadding the alcohol as a separate step, the resin may be and preferablyis prepared in contact with the alcohol for the etherification. In thisalternative method, the dicy, formaldehyde and alcohol are heatedtogether. The heating is eifected first in contact with the catalyst forthe condensation of dicy and formaldehyde, to give the tetramethylol 4derivative. Then, after this derivative has been formed, there is addedthe acid catalyst of the etherification of the alcohol with thepolymethylol derivative first formed.

This invention will be further illustrated by description in connectionwith the following specific examples of the preparation of the newethers or alkyl compounds.

In these examples and elsewhere herein, proportions are expressed asparts by weight unless specifically stated to the contrary.

Example 1 A mixture was made of 168 parts dicy (2 mols), 600 partsMethyl Formcel, and 3.6 parts of borax serving as catalyst. The MethylFormcel i the commercial mixture containing 40% of formaldehyde, 53% ofmethanol and 7% of water. This corresponds to 4 mols of formaldehyde andapproximately 5 'mols of methanol for each mol of the dicy.

The mixture was refluxed at 83.0 C. for four hours. At that stage thematerial had become what is called a polymethylol derivative of the dicyand also water soluble, that is, non-precipitating on strong dilutionwith water.

There was then added glacial acetic acid as catalyst of etherification.Whereas the pH immediately before the addition of the acid was 8.8, thepH after the acetic acid addition was 6.8. The proportion of acetic acidused was 12 parts (0.2 mol).

The whole was then refluxed again at 83 C. for two hours. At the end ofthis time the mixture was non-precipitable on dilution with a largevolume of alcohol or on the addition of an equal volume of 5% saltsolution. Also the product was soluble in water.

The product is the polymethyl ether of the polymethylol dicy resin. Itis considered that the poly in this case has a numerical value of atleast 4 methylol groups, some or all of which are alkylated, to form themethyl ether. It is considered also that the reaction of the methylolgroups and the molecules of methanol may be represented for convenienceas follows:

In this equation, R represents a portion of the intermediate dicy resin,that is, the resin less 4 methylol groups or the original dicyandiamideless the 4 hydrogens.

Ezcajrmple 2 The procedure of Example 1 is followed except that themethyl component of the Methyl Formcel is replaced by an equalproportion by weight of the n-propyl radical. In other words, the MethylFormcel is replaced by an equal weight N-Propyl Formcel containing again40% of the formaldehyde and in this instance 53% of n-propyl alcohol.

Example 3 The procedure of Example 1 is followed except that the MethylFormcel therein used is replaced by an equal molecular proportion ofButyl Formcel containing the same percentage of butyl alcohol as ofmethanol and the same percentage of formaldehyde as in Example 1. Theproduct is soluble in alcohol and in xylol and like hydrocarbonsolvents.

Example 4 The procedure of Example 1 is followed except that the MethylFormcel therein used is replaced'by 4 mols of formaldehydeand fourequivalent weights of any one of the water soluble monohydric andpolyhydric alcohols named earlier herein.

Example 5 Dicy and formaldehyde resin was prepared in solution, asdescribed in the said copending application and also as described above,and then dried, as by spray or vacuum drying, the ratio of formaldehydeused being 4 mols to 1 mol. The dried material is then acidified to pH6.8 with acetic acid and mixed with any of the alcohols listed above.The alcohol, when monohydric, is used in the ratio of 4 to mols for 1mol of .dicy when the alcohol is a lower monohydric alcohol and l to 4mols when the alcohol is polyhydric alcohol. The mixture is then heatedat 80 C. until reaction substantially ceases. The product is soluble inalcohol.

Example 6 168 parts of dicyandiamide (2 mols) and 600 parts of PropylFormcel (8 mols of formaldehyde), with no borax added, were refluxed for4 hours at 80 C. Then there were added 596 parts castor oil fatty acids.The whole was heated 8 hours at 85-90 C. and then for 5 hours at 95 C.

The product was soluble in 91% alcohol, insoluble in water, and solublein xylol.

Example 7 84 'parts of dicyandiamide were heated with 300 parts N-PropylFormcel. After minutes at 60 C., the mixture became clear. It was thenheated for 4 hours at 80 C. There were then added 280 parts linseed oilfatty acids. This gave a cloudy mixture. After 2 hours heating theproduct became clear. Heating was continued for 5 hours more at 80 C.

Example 8 84 parts of dicyandiamide (1 mol), part borax, and 300 partsN-Propyl Formcel (4 mols formaldehyde) were refluxed 4 hours at 70 to 80C. 250 parts China-wood oil fatty acids (1 mol) were then added and thewhole heated to 85 to 90 C. for 5 hours.

Example 9 84 parts of dicyandiamide, 300 parts of N-Propyl Formcel, and280 parts of white oleic acid were heated for 7 hours at 70 to 80 C.This gave a clear product.

The products of Examples 6, 7, 8, and 9 are insoluble in water butsoluble in alcohol. They are useful resins for paint and varnishformulation. The higher fatty acids used replace the acidic catalystssuch as acetic acid of the earlier examples. The product is an acidcolloid of n-propanol alkylation compound of the dicy resin.

Example 10 204 parts of spray dried resin made by evaporation of theliquid product (1 mol) of said copending application, now issued asPatent 2,567,238, and 368 parts of glycerine were heated on the waterbath at 80 C. until the resin dissolved. Then there were added 12 partsof glacial acetic acid (0.2 mol). The whole was heated for 2 hours at 95C. and then for 1 hour under vacuum, to complete the alkylation.

Example 11 42 parts of dicyandiamide (0.5 mol) and 187 parts of MethylFormcel (2.5 mols of formaldehyde) were heated until clear at C. (4hours) and then the whole was mixed with 141.5 parts of stearylamide.The mixture was then heated 3 hours at 80 G. Then there were added 30parts glacial acetic acid and the resulting mix heated for 4 hours. Then406.5 parts of water were added to reduce the concentration to 30%. Theamide used is considered to replace a part of the alkyl groupsintroduced in the etherification described above. The product as made isa white stable, water dispersible paste. It is useful as textile sizingand as a water repellent.

Example 12 400 parts of polyethylene glycol (1 mol) and 30 parts ofparaformaldehyde were heated to C. The temperature then rose momentarilyto 130 C. The mixture was then cooled to C. and held there for 1 hourand 15 minutes. Then there were added 84 parts of dicyandiamide (1 mol)Then the temperature was maintained at95 C. for 1 hour. Then 225 partsof Methyl Formcel were added and refluxed 3 hours at 95 0. Then 60 partsof glacial acetic acid (1 mol) were added and the whole refluxed 2 hoursat 95 C.

The products made with polyhydric alcohols are soluble in water and to alimited extent in alcohol.

Example 13 The product of Examples 1, 2, or 3 is mixed with 4 mols of ahigher (C4 to C18) aliphatic alcohol such as butyl, dodecyl, oroctadecyl and the mixture boiled and fractionated until practically nomore of the lower alcohol originally present passes out of thefractionation system.

The product is the ether of the polymethylol derivative of dicy with theselected one of the C4 to C18 alcohols. The product is soluble inalcohol and xylol.

Example 14 The procedure of Example 13 is repeated except that the C4 toC18 alcohol is replaced by a sugar such as dextrose, levulose, sucrose,or maltose, in proportion to provide 4 hydroxyl groups for each mol ofdicy represented in the polymethylol derivative of the dicy.

The liquid mixtures made as described in the examples above may beneutralized, as with sodium carbonate or other alkali, to bring aciditydown to about pH 7. Ordinarily this neutralizing is not required,particularly when the acid catalyst used is a weak acid.

When dried many of the products of the examples are pasty liquids.

It will be understood that it is intended to cover all changes andmodifications of the examples of the invention herein chosen for thepurpose of illustration which do not constitute departures from thespirit and scope of the invention.

What is claimed is:

1. In making a water soluble resin that is stable in aqueous solution,the method which comprises contacting dicyandiamide in aqueous solutionwith formaldehyde in the proportion of 3.6-5 mols for 1 mol of thedicyandiamide, adding an alkaline material in amount to establish the pHat a level above 7, maintaining contact of the dicyandiamide,formaldehyde and said material at an elevated temperature until thecondensation occurs and the resulting product passes through a waterprecipitable stage to the water non-precipitable stage, introducing anunsubstituted aliphatic alcohol containing 13 carbon atoms to themolecule, introducing an acidic material after the said non-precipitablestage has been reached and in amount to lower the pH to a level below'7, and maintaining the resulting mixture at an elevated temperature,causing etherification, until substantially no more etherificationresults.

2. The method of claim 1 in which the alcohol is introduced after thesaid non-precipitable stage has been reached.

3. The method of claim 1 in which the proportion of the aliphaticalcohol used is at least approximately 4 mols to 1 mol of dicyandiamideused.

4. In making a water soluble resin that is stable in aqueous solution,the method which comprises warming a mixture of dicyandiamide,formaldehyde in the proportion of 3.6-5 mols for 1 mol of dicyandiamide,water, and an unsubstituted aliphatic alcohol containing 1-3 carbonatoms to the molecule at a pH above 7 until the tetramethylol derivativeof dicyandiamide results and then at a pH below '7 until etherificationof the said derivative with the said aliphatic alcohol is produced.

5. A resin characterized by being water soluble and non-gelling andresistant to precipitation by electrolytes in aqueous solution, theresin being the ether of a water soluble unsubstituted aliphatic alcoholcontaining 1-3 carbon atoms to the molecule with the polymethylolderivative of dicyandiamide, the said derivative being the product ofreaction of dicyandiamide with formaldehyde in the proportion of 3.6-5mols to 1 mol of the dicyandiamide at a pH above '7 and the resin beingthe product of the method of claim 1.

6. In making a resin that is stable in contact with water, the methodwhich comprises contacting dicyandiamide in aqueous solution withformaldehyde in the proportion of 3.6-5 mols for 1 mol of thedicyandiamide, adding an alkaline material in amount to establish the pHat a level above 7, maintaining contact of the dicyandiamide,formaldehyde and said material at an elevated temperature untilcondensation occurs and the condensation product passes through a waterprecipitable stage to the stage of being nonprecipitable by water,introducing an alcohol, introducing an acidic material after the saidcondensation has occurred and in amount to lower the pH to a level below7, and maintaining the resulting mixture at an elevated temperature,causing etherification, until substantially no more etherificationoccurs, the alcohol being one selected from the group consisting ofmethanol, ethanol, isoand n-propanol; ethylene, propylene, butylene, andpolyethylene glycol; glycerine; pentaerythritol; sorbitol; and dextrose,levulose and sucrose.

7 A resin characterized by being water soluble and resistant toprecipitation by electrolytes in aqueous solution, the resin being theether of a water soluble aliphatic alcohol with the polymethylolderivative of dicyandiamide, the said aliphatic alcohol being oneselected from the.

group consisting of methanol, ethanol, isoand n-propanol; ethylene,propylene, butylene, and polyethylene glycol; glycerine;pentaerythritol; sorbitol; and dextrose, levulose, and sucrose, and theresin being the product of the method of claim 6.

8. A resinous composition comprising the combination of a higher fattyacid with an ether of the water soluble resinous condensation product of3.6 to 5 mols of formaldehyde with 1 mol of dicyandiamide, the saidether being that described in claim '7.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,317,181 DAlelio Apr. 20, 1943 2,567,238 Sellet Sept. 11,1951 FOREIGN PATENTS Number Country Date 545,081 Great Britain May 11,1942 850,892 France Sept. 18, 1939 OTHER. REFERENCES Powers, SyntheticResins and Rubbers, page 86, John Wiley and Sons, Inc., New York (1943)

1. IN MAKING A WATER SOLUBLE RESIN THAT IS STABLE IN AQUEOUS SOLUTION,THE METHOD WHICH COMPRISES CONTACTING DICYANDIAMIDE IN AQUEOUS SOLUTIONWITH FORMALDEHYDE FOR 1 MOL OF THE DICYANDIAMIDE, ADDING AN ALKALINEMATERIAL IN AMOUNT TO ESTABLISH THE PH AT A LEVEL ABOVE 7, MAINTAININGCONTACT OF THE DICYANDIAMIDE, FORMALDEHYDE AND SAID MATERIAL AT ANELEVATED TEMPERATURE UNTIL THE CONDENSATION OCCURS AND THE RESULTINGPRODUCT PASSES THROUGH A WATER PRECIPITABLE STATE TO THE WATERNON-PRECIPITABLE STAGE, INTRODUCING AN UNSUBSTITUTED ALIPHATIC ALCOHOLCONTAINING 1-3 CARBON ATOMS TO THE MOLECULE, INTRODUCING AN ACIDICMATERIAL AFTER THE SAID NON-PRECIPITABLE STAGE HAS BEEN REACHED AND INAMOUNT TO LOWER THE PH TO A LEVEL BELOW 7, AND MAINTAINING THE RESULTINGMIXTURE AT A ELEVATED TEMPERATURE, CAUSING ETHERIFICATION, UNTILSUBSTANTIALLY NO MORE ETHERIFICATION RESULTS.